HVAC inside and outside return air control system

ABSTRACT

An inside and outside air return control system for a HVAC unit that includes an outside air conduit connected to the inside air return duct and a flap valve that selectively moves to control the delivery of inside air or outside air to the air return duct in the HVAC unit. The system also includes a programmable control panel connected to the HVAC unit&#39;s air conditioner or heat pump and to the furnace or air handler. The control panel is also connected to an inside thermometer and an outside thermometer. During operation, the control panel continuously monitors the air temperatures inside and outside the residence. During setup, a control temperature is selected in the control panel. The readings from the two thermometers are compared with the control temperature and used to control the movement of the flap valve so that the cooler air source is delivered to the air return duct.

This is a utility patent application which claims benefit of U.S. Provisional Application No. 61/134,678 filed on Jul. 10, 2008.

COPYRIGHT NOTICE

Notice is hereby given that the following patent document contains original material which is subject to copyright protection. The copyright owner has no objection to the facsimile or digital download reproduction of all or part of the patent document, but otherwise reserves all copyrights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The following invention pertains to air return systems used with heating, ventilation, and air conditioners (called HVAC systems) and more particularly, to such systems that automatically control the source of return air based on external conditions.

2. Description of the Related Art

Many residential HVAC systems include an outdoor air conditioner or heat pump unit connected to an indoor furnace or air handler. The HVAC units typically connect to a set of indoor coils that cool the inside air just before it is delivered to a supply duct that carries the cool air throughout the house. The inside air is returned to the HVAC unit via an inside vent and air return duct. An air filter unit is typically placed between the main return duct and the furnace or air handler. A control panel connects to the HVAC unit to control its operation so that the inside temperature is maintained at a desired temperature throughout the day and night.

The cost of electricity is increasing and many homeowners are looking for ways to reduce costs. In many regions, the outside air temperature drops quickly after sunset or during the evening. Eventually, the temperature of the outside air may drop below the houses inside temperature. In some instances, the homeowner may turn OFF the HVAC unit and open the windows so that the outside air flows into the house during the night.

If the homeowner decides to turn off the HVAC unit at night and open the windows, ideally he or she should do so only after the outside air temperature drops below the desired inside air. Unfortunately, the outside air temperature may drop during the night after the homeowner has fallen asleep.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a simple, inexpensive method of selectively controlling the source of return air used by the HVAC unit.

It is another object of the present invention to provide such a system that can be easily adaptable to a house's existing HVAC unit.

It is a further object of the present invention to provide such a system that allows the user to select different temperature differential between the inside and outside temperature before the system is activated.

These and other objects are met by the inside air and outside intake air control system used with residential HVAC units. The system is designed to automatically regulate the use of cool inside as return air to the HVAC unit or use outside air when the outside air temperature drops below a pre-selected temperature. By using outside air that is cooler than the inside air, the HVAC may operate more efficiently.

The system includes the installation of an outside air conduit that connects to the HVAC's unit inside air return duct. Disposed between the outside air conduit and the inside air return duct is a flap valve that can be selectively opened or closed to control the flow of inside return air or fresh outside air to the HVAC unit's furnace or air handler. The flap valve is connected to a modified control panel unit that in addition to being used to control the HVAC's system, also monitors both the inside and outside air temperatures. When the outside air temperature exceeds a pre-selected control temperature set by the operator, the flap valve moves to a first position so that only inside air is recycled to the HVAC unit. When the outside air temperature drops below the pre-selected temperature, the flap valve moves to a second position so that only outside fresh air is delivered to the HVAC unit.

In addition, the system may include a modem or network card attached to the HVAC unit that allows the HVAC to communicate with a LAN or WAN.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a typical residential HVAC system that includes an air conditioner/heat pump, connected to an indoor coil system mounted above a furnace or air handler that delivers cool air to an inside supply air duct and then back through an inside air duct and eventually back to the furnace or air handler.

FIG. 2 is an illustration of the inside air and outside control system showing the inside air being recycled through a vent control valve and though the house.

FIG. 3 is an illustration of the inside air and outside control system showing the outside air being delivered through the vent control valve and through the house.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to the FIGS. 1-3, there is shown an inside air and outside intake air control system, generally indicated by the reference number 10, designed primarily to be used with residential or small building HVAC unit 12. The system 10 is designed to automatically regulate the use of cool inside cool air as return air to the HVAC unit 12 or use of outside air when the temperature of the outside air drops below a control temperature selected on the control panel. By using outside air that is cooler than inside air, the HVAC unit 12 operates more efficiently.

The control system 10 is designed to be incorporated into an existing HVAC unit 12 that include an outdoor air conditioner or heat pump unit, generally indicated by the reference number 15. The air conditioner or heat pump unit 15 is connected to an indoor furnace or air handler, generally indicated by the reference number 20. The air conditioner or heat pump unit 15 is connected to an indoor coil unit 30 located inline with the furnace or air handler 20 which cools the air 90 located therein just before it is delivered to a supply duct 35 that then carries the cool air, designated 92 throughout the house 99. The air 92 when distributed in the house 99 becomes warm (now designated 94) and is eventually returned to the HVAC unit 12 via an inside vent 96 and air return duct 98. The air return duct 98 acts or may be connected to a large main return duct 99 which then delivers the warm air 94 back to furnace or air handler 20. An optional air filter unit 85 may be placed between the main return duct 98 and the furnace or air handler 20. During operation, the central control panel 70 monitors the inside temperature of the house so that the temperature of the air 94 is maintained at a desired temperature throughout the day and night.

The system 10 is designed to connect to an existing or a new installation of the HVAC unit 12. The system 10 includes the installation of an outside air conduit 50 that connects to the inside air return duct 98. Disposed between the outside air conduit 50 and the inside air return duct 98 is a flap valve 60 that can be selectively opens or closes to control the flow of inside return air or fresh outside air 101 to the HVAC unit 12. The flap valve 60 is connected to the control panel 70 that connects to an inside thermometer 75 that measures the temperature of the inside air 94. The control panel 70 also connects to an outside thermometer that measures the temperature of the outside air 80 located adjacent to the outside vent 100 on the air conduit unit. The control panel 70 includes a PCB unit 72 with manual control buttons 73 that enables the operator to select a control temperature designated by reference number 79. When the outside air temperature 100 exceeds the control temperature 79, the flap valve 60 automatically moves to a first position so that only inside air 94 is recycled to the HVAC unit 12 (see FIG. 2). When the outside air temperature 101 drops below the control temperature 79, the flap valve 60 automatically moves to a second position (see FIG. 3) so that only outside fresh air 101 is delivered to the HVAC unit 12. In the preferred embodiment, the control temperature 79 is a temperature within a range of temperatures three to five degrees above the outside temperature 101.

It's shown in FIG. 2, the control panel 70 may be connected to a network card on modem 110 that allows the control panel 70 to a local area network 115, so that the user may communicate with the control panel 70 via a desktop or laptop computer inside the building. The network card or modem 110 may be connected to a wide area network 120 that allows the user to communicate with the control panel 70 from a remote location via a desktop, laptop or cellular telephone.

In compliance with the statute, the invention described herein has been described in language more or less specific as to structural features. It should be understood however, that the invention is not limited to the specific features shown, since the means and construction shown, is comprised only of the preferred embodiments for putting the invention into effect. The invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the amended claims, appropriately interpreted in accordance with the doctrine of equivalents. 

1. An inside and outside air control system for a HVAC system, comprising: a. a HVAC unit that includes an outside air conditioner or heat pump an inside coil unit connected to said air conditioner or heat pump, a furnace or air handler connected to said inside coil unit, a supply duct connected to said inside coil unit, and an inside air return duct connected to said furnace or air handler; b. a control panel connected to said HVAC unit; c. an inside thermometer connected to said control panel used to monitor the temperature of the inside air; d. an outside thermometer connected to said control panel used to monitor the temperature of the outside air; e. an outside air duct that connects at one end to an outside air source and at the other end to said air return duct; f. a flap valve disposed between said outside air duct and said air return duct to control the air returned to said furnace or air handler; and, g. a programmable main thermostat located inside said control panel that controls operation of the air conditioner or heat pump and said furnace or air handler, said main thermostat also connected to said inside thermometer, said outside thermometer, and said flap valve, said main thermostat being able to monitor the inside temperature and the temperatures of the inside and outside air and selectively control the position of the flap valve so that inside air is recycled when the inside air temperature is with a temperature range from a control temperature and outside air is delivered to said return duct when the inside air is above the control temperature.
 2. The air control system, as recited in claim 1, further including a communication means connected to said control panel that allows said main thermostat to be monitored and selectively adjusted. 